Liquid crystal display elements are display elements having a thin thickness, a light weight, and a low power consumption among various display elements. This leads to wide application of liquid crystal display elements to, for example, image display apparatuses such as televisions, and OA (Office Automation) apparatuses such as personal computers.
Conventionally known liquid crystal display methods (display mode) of the liquid crystal display elements include, for example, a TN (Twisted Nematic) mode in which a nematic liquid crystal is used, display modes in which FLC (Ferroelectric Liquid crystal) or AFLC (Antiferroelectric Liquid crystal) is used, an IPS (In-plane Switching) mode, and an FFS (Fringe Field Switching) mode (See Patent Document 1).
Among the liquid crystal display methods, for example, the TN mode is conventionally adopted in the liquid crystal display elements in practical use. The liquid crystal display elements using the TN mode have drawbacks such as a slow response and a narrow viewing angle.
Moreover, the display modes in which the FLC or AFLC is used, are advantageous in their fast responses and wide viewing angles, but significantly poor in resistance to shocks, temperature characteristics, and the like. Therefore, the display modes in which the FLC or AFLC is used have not been widely used in practical use.
Moreover, the IPS mode and FFS mode perform displaying by switching liquid crystal molecules in a plane and have a wide viewing angle. Like the TN mode, however, the IPS mode and FFS mode are disadvantageous in a slow response. This disadvantage is a significant hindrance for the IPS mode and FFS mode to take over CRT (Cathode Ray Tube).
In all the foregoing liquid crystal display methods, liquid crystal molecules are oriented in a certain direction and thus a displayed image looks differently depending on an angle between a line of vision and a direction in which the liquid crystal molecules are oriented. On this account, all these display methods have limitations to viewing angles, respectively. Moreover, all the display methods utilize rotation of the liquid crystal molecules, the rotation caused by application of an electric field on the liquid crystal molecules. Because the liquid crystal molecules are rotated in alignment all together, responses take time in all the display method. Liquid crystal display elements using the display mode in which the FLC or the AFLC is used are advantageous in terms of response speed and viewing angle, but have a problem in that their alignment can be irreversibly destroyed by an external force.
In contrast to those liquid crystal display elements in which rotation of molecules by the application of the electric field is utilized, a liquid crystal display element in which a material having an optical anisotropy by and according to electric field application is used is proposed. Especially, a liquid crystal display element in which a material showing an orientation polarization due to electro-optical effects is utilized or a liquid crystal display element in which a material showing electronic polarization is used is proposed.
The electro-optical effect is a phenomenon in which a refractive index of a material is changed by an external electric field. There are two types of electro-optical effect: one is an effect proportional to the electric field and the other is proportional to the square of the electric field. The former is called the Pockels effect and the latter is called the Kerr effect.
Materials showing the Kerr effect were adopted early in high-speed optical shutters, and have been practically used in special measurement instruments. The Kerr effect was discovered by J. Kerr in 1875. So far, for example, organic liquids such as nitrobenzene, carbon disulfide, and the like, are known as materials showing the Kerr effect. These materials are used, for example, in measuring strength of high electric fields of power cables or the like, other than in the aforementioned optical shutters.
Later on, it was found that liquid crystal materials have large Kerr constants. Researches have been conducted basic research to utilize the liquid crystal materials having the large Kerr constants in light modulation devices, in light deflection devices, and further in optical integrated circuit. It has been reported that some liquid crystal compound has a Kerr constant more than 200 times higher than that of nitrobenzene.
Under these circumstances, studies for using the Kerr effect in display apparatuses have begun. The refractive index of the materials showing the Kerr effect is proportional to square of the electric field applied on the material. Because of this, a relatively lower voltage driving is expected in the utilization of orientation polarization of a material showing the Kerr effect than in the utilization of orientation polarization of a material showing the Pockels effect. Further, it is expected that a material showing the Kerr effect is applied to a high-speed response display apparatus because a material showing the Kerr effect has a response property of several p seconds to several m seconds, as its basic nature.
For instance, Patent Documents 2 and 3 suggest display elements in which a medium made from a liquid crystalline material is sealed between a pair of substrates and the Kerr effect is induced by application of an electric field parallel to the substrates.    [Patent Document 1]    Japanese Unexamined Patent Publication No. 202356/1999 (Tokukaihei 11-202356 (published on Jul. 30, 1999))    [Patent Document 2]    Japanese Unexamined Patent Publication No. 2001-249363 (Tokukai 2001-249363 (published on Sep. 14, 2001))    [Patent Document 3]    Japanese Unexamined Patent Publication No. 183937/1999 (Tokukaihei 11-183937 (published on Jul. 9, 1999))    [Patent Document 4]    Japanese Unexamined Patent Publication No. 221726/2002 (Tokukai 2002-221726 (published on Aug. 9, 2002))    [Non-Patent Document 1]    Jun Yamamoto, “Liquid Crystal Microemulsion”, EKISHO, 2000, Vol. 4, No. 3, p. 248-254    [Non-Patent Document 2]    Yukihide Shiraishi and four others, “Palladium Nanoparticles Protected By Liquid Crystal Molecules—Preparation and Application to Guest-Host Mode Liquid Crystal Display Element”, KOBUNSHI RONBUNSHU (Japanese Journal of Polymer Science and Technology), December 2002, Vol. 59, No. 12, p. 753-759    [Non-Patent Document 3]    D. Demus and three others, “Handbook of Liquid Crystals Low Molecular Weight Liquid Crystal”, Wiley-VCH, 1998, Vol. 2B, p. 887-900    [Non-Patent Document 4]    Jun Yamamoto, “Liquid Crystal Scientific Experiment Course 1: Identification of Liquid Crystal Phase: (4) Lyotropic Liquid Crystal”, EKISHO, 2002, Vol. 6, No. 1, p.    [Non-Patent Document 5]    Eric Grelet and three others, “Structural Investigations on Smectic Blue Phases”, PHYSICAL REVIEW LETTERS, The American Physical Society, Apr. 23, 2001, Vol. 86, No. 17, p. 3791-3794    [Non-Patent Document 6]    Takashi Kato and two others, “Fast and High-Contrast Electro-optical Switching of Liquid-Crystalline Physical Gels: Formation of Oriented Microphase-Separated Structures”, Adv. Funct. Mater., April 2003, Vol. 13. No. 4, p. 313-317    [Non-Patent Document 7]    Hirotsugu Kikuchi and four others, “Polymer-stabilized liquid crystal blue phases”, p. 64-68, [online], Sep. 2, 2002, Nature Materials, Vol. 1, [searched on Jul. 10, 2003], Internet <URL: http://www.nature.com/naturematerials>”